1. Technical Field
The present invention relates to an image projecting system. More specifically, the present invention relates to an image projecting system that corrects distortion of images projected by an image projecting apparatus.
2. Description of the Related Art
The projectors, which are widely used as image projecting apparatuses, have recently improved in resolution of liquid crystal panels, brightness of light source accompanied by increased efficiency in lamps, lowering the cost, and so on. For example, a compact and lightweight image projecting apparatus using a digital micro-mirror device (DMD) has spread and become widely used in homes as well as offices and schools.
Such an image projecting apparatus projects images on a projection surface, such as a screen. However, a wall or the like may also be used as the projection surface, which may be sometimes distorted like a curved surface. Further, the image projecting apparatus may sometimes be placed while being tilted relative to the projection surface. In such case, a resulting image may be affected by a trapezoidal distortion, depending on a relative relation between the projection light axis of the image projecting apparatus and the projection surface. In particular, an ultra short throw image projecting apparatus is vulnerable to flexure of the projection surface, as even a small flexure of the screen is emphasized, such that distortion correction is required.
In view of the above, a projector system that uses a personal computer capable of correcting distortion has been known. The projector obtains data of tilt angles in vertical and/or horizontal directions between the projection surface and the projection light axis. The personal computer corrects video data output from the projector based on the tilt angle data sent by the projector, and outputs the corrected video data to the projector.
Meanwhile, simplified functions and lower cost have been desired for the image projecting apparatus. For example, if the projector includes a tilt sensor (acceleration sensor), a light intensity measuring sensor, etc. for distortion correction, the simplification or the lower cost would not be realized.